The background of this invention is described as it relates to the filtering of paint, although it will be understood from the disclosure to follow that the invention is also applicable to the filtering of other materials, as well as uses in food processing.
When professional painters use an airless spray gun, they first filter or strain the paint so it will not clog the tiny nozzle in the spray gun. Typically, the do-it-yourself user of an airless spray gun bought at the local hardware store is unaware that paint should be filtered before use. As a result, an airless spray gun is often clogged after a single use, after the paint in it has dried; and the spray gun cannot be reused unless a new nozzle is purchased and installed.
The present invention is a system that professional painters or do-it-yourself painters can use to strain or filter paint prior to using the paint in an airless spray gun.
In the prior art, professional painters have typically filtered paint prior to using the spray equipment by first placing a filter cloth inside an empty paint bucket. The painter then pours the paint into the interior of the filter cloth so the paint passes through the pores of the filter to strain the paint. Since the prior art filter cloth extends down to near the bottom of the bucket, the painter must pour the paint into the bucket and then pull the filter cloth up out of the bucket to ensure that all paint passes through the cloth and into the bucket. This job is inconvenient, messy, tedious, and places a strain on the painter's back when constantly filtering paint in this manner. The filter cloth is often pulled into the bucket by the weight of the paint, and consequently, unfiltered paint will spill into the bucket, slowing down the filtering process. A tapered bottom of the conventional filter cloth also can tend to cause the paint to clog the bottom of the filter cloth, which also slows down the filtering process. When the painter pulls the filter cloth upwardly from the bucket, the clogged bottom portion adds weight to the filter, placing a strain on the back of the painter, who must hold the filtering cloth over the bucket until all the paint has finally passed through it.
My U.S. Pat. No. 4,946,591 describes an improved filter support which solves these problems by making it possible to filter paint by pouring it through a filter cloth mounted inside the support which, in turn, rests in an upright position above the top of the bucket. The invention is especially useful in filtering paint quickly and easily. For straining paint, the strainer assembly is placed on top of an empty container, and the filter medium is simply taped to the exterior of the support for holding it in place inside the support and above the top of the container. The paint is then poured through the filter cloth so the paint passes through the filter and then into the container below relatively easily without clogging the bottom of the filter. No complex mechanical parts need to be assembled or disassembled, and filtering is done in a clean manner. Debris cannot enter the filtered paint, and the paint which has been filtered does not skin over during hot weather.
The present invention provides improvements to the filter supports disclosed in my '591 patent, and these improvements include reduced expenses in manufacturing the tubular support, providing a convenient means for attaching the filtering cloth to the support, and a useful means for stacking the strainer supports in a large stack without having the supports stick together in the stack.